Telephone receiving instrument.



T. B. MILLER.

TELEPHONE RECEIVING INSTRUMENT.

APPLICATION FILED SEPT.25,1912.

1,1 14,902, Patented Oct. 27, 1914.

WITNESSES: INVENTOH F 1 6 7%0/2225 fizz/"700 /V///6/ A TTOR/VE Y STATES PA OFFICE.

THOMAS BURTON MILLER, OF SEATTLE, WASHINGTON, .ASSIGNOB OF ON E HfALF TO SMITH GA'NNE-RY- MACHINES COMPANY OF sEATTLE wAfiHlNGToN, A COBPORA TION. OF WASHINGTON.

TELEPHONE RECEIVING INSTRUMENT.

Specification of LcttersePatent.

Patented Oct. 27. 1914.

Application filed September 25, 1912. Serial No. 722,167.

Seattle, in the county of King and State of Washington, have invented a certain new and useful Improvement in Telephone Receiving Instruments, of which the followin is a specification.

y invention relates to improvements in telephonic receiving instruments, but more particularly itrelates to that class of telephone receiversthat are employed in wireless telegraph systems for receiving successive combinations of sounds representing the letters of the well known alphabetic codes, the Morse and the Continental; and the object of my improvement is to provide a receiving instrument whose diaphragm shall be actuated to give perceptible sounds in response to minutest variations .in .the electrical condition of a circuit within which such telephone is included whereby the slightest amount of electrical energy in form of waves or oscillations in such circuit mayv be Iperceived.

attain this object by devices which are illustrated diagrammatically in the accompanying drawing wherein 15 shown a pole portion of permanent steel magnet 1 to which is attached a soft iron electro-magnet core which comprises a lower end portion 2, a constricted portion 3 and an upper end portion 4 the said upper'end' portion 4 be-' ing rovided with a longitudinal slot 5 which serves, in accordance with a well known principle, to obviatethe generation of eddy currents. The permanent steel magnet 1 may, if it be desired, be replaced by an electro-magnet that is associatedwith suitable well known means for maintaining it in a magnetized condition. A helix 6 of insulated magnet wire is disosed'to surround the lower end portion 2 o the soft wire iron electro-magnet core while a similar helix 7 surrounds the upper end portion4 thereof.

As shown in the drawing, the inner terminals of the helices 6' and 7 are both connected to a circuit wire 8 while-their outerterminals are both connected with a circuit wire 9 whereby electricityv flowing from circuit wire 8 to circuit wire 9 would find passageway through both helices 6 and 7, but in the helix 6 the electricity would flow in one direction around the lower end portion 2 while in the .core to a helix 7 it would flow in the op osite direction around the upperend portion 4jof the soft iron electro-magnet core. The helices 6 and 7- being connected in multiple to the circuit wlres 8 and 9 electricity would find a path through wire 8 to the inner terminals of the helices 6 and 7 there to divide and after passing one half through the helix 6 and the other half through the helix 7 the electricity .would reunite where the outer terminals .of said helices 6 and 7 connect with the circuit wire 9, as shown. The efiect of waves of electrical energy flowing in opposite directions through the helices 6 and 7 is obvious and I have found such form of device to give remarkably eflicient results with respect to sensitiveness in detecting sllght electrical disturbances in a circuit with which it was-connected. Of course such arrangement of helices and circuit connections would give no useful results if the magnet core be not constricted as by the constricted portion 3. A diaphragm 10 is supported by suitable well known means (not shown) with its central portion adjacent to the face of the upper end portion 4 of the soft iron electro-magnet core, in the usual manner, it being clamped in its osition by an ear-piece of well known orm,

which is indicated diagrammatically by the curved lines 11 in the drawing. By such construction the magnetic lines of force emanating from the upper portion 4 of the electromagnet core to flow across the space or gap to the diaphragm 10 are so restricted that such diaphragm 10 is magnetized to a degree below the point of saturation and is therefore more susceptible to changes in the number of such magnetic lines of force, but such diaphragm 10 is sufliciently magnetized normally to beattracted toward the face of the upper portion 4 of the electro-magnet oint where the attractive force balances t e retractile force due to the elastic or resilient quantity of such diaphragm 10, at which point such diaphragm 10 is more sensitive to the slightest degree of variation in the amount of magnetic flux between the face of said upper portion 4 of the electro-magnet and the said diaphragm 10.

Manifestly various forms of permanent steel magnets and various forms of electromagnets may be substituted for the permanent steel magnet 1, indicated in the drawing, and the dimensions of various parts of my invention may parting from the spirit thereof.

What I claim is:

lln a receiving telephone, the combination with a diaphragm, of an elective-magnet core that is constricted in a portion of its length, one end of which electro-magnet core is disposed adjacent to the central portion of said diaphragm, magnetic means associated with the other end of said eleotro-magnet core Liny name this seventeenth day of Septemberwhereby such electro-magnet core may be supplied 'Withmagnetio lines of forc'e'of constant polarity,' and tWo helices of magnet wire disposed one of the portions of said electro-magnet core between Which portions said electrobe changed Without deeach to surround a difierent magnet core is constricted, said two helices being electrically connected with each other to adapt them to be connected to a receiving circuit in parallel With each'other so that a portion of an electric current flowing in such receiving circuit would flow around one portion of said eleotro-magnet core in one direction while the other portion of such electric current would flow 1n an opposite direction around the other portion of said electromagnet core.

In Wrtness whereof, I, hereunto subscribe THQMAS'BURTON MILLER. Witnesses:

F. G. MATHENY, ANNA ltllesnms, 

